Party-line automatic telephone system



Oct 8, 1929. R. G. RKZHARDSON ErAL PARTY LINE AUTOMATIC TELEPHONE SYSTEMOriginal Filed Feb. 25, 1925 2 Sheets-Sheet Oct. 8, 1929. R. G.RICHARDSON ET AL 1,731,217

PARTY LINE AUTOMATIC TELEPHONE SYSTEM Original Filed Feb. 23, 1923 2Sheets-Sheet 2 rm Rodney EE1chards0nand-Juhn I. B elZam Patented Dot. 8,19.29

UNITED STATES PATENT OFFICE RODNEY G. RICHARDSON, F CHICAGO, AND JOHN I.BELLAMY, 0F BROOKFIELD, ILIaI- NOIS, ASSIGNORS, BY MESNE ASSIGNMENTS, T0AUTOMATIC ELEC'IRIG ING, OF CHICAGO, ILLINOIS, A C ORPORATI'EON 0FDELA'WARE PARTY-LINE AUTOMATIC TELEPHONE SYSTEIVL The present inventionrelates to selective ringing party line telephonesystems in gen mentusedin a system of this nature to select the ringing current is reduced to aminimum.

Other objects will be met with and explained from time to time duringthe course of the specification.

In order to carry out the main obj cct of the invention, the ringing ofcalled stations is divided into as many periods as there are stations ona line, and ringing current of the proper sort to signal one stationonly, is placed on the common ringing circuit during each period. Then,to call-the desired station on a party line, it is necessary only toconnect the common ringing circuit to the line during the proper period.This is accomplished by a ringing relay in the connector circuit whichis connected to one of a plu rality of pick-up conductors, dependingupon the station being called. This ringing relay, upon energizing overone of the pick-up conductors, which it does when the source of ringingcurrent corresponding to the pick-up conductor in use is connected tothe common ringing circuit, connects the common ringing circuit to thecalled line and maintains the connection until the end of that ringingperiod is reached. The ringing relay operates the same way each timethat ringing period recurs.

The accompanying drawings, comprising Figs. 1 and 2, show by means ofthe usual circuit diagrams a sutlicient amount of apparatus in a systemembodying the principles of the invention to enable the invention to beex plained and understood. In order for Figs.

' Original application filed February 23, 1323, Serial No. 620,603.Divided and this application filed January Serial No. 84,261.

1 and 2 to be understood best, they should be arranged in order with thecorresponding lines at the ends thereof in alignment.

Figure 1 shows the substation A of which the line terminates at theexchange in the line switch C, and the selector E which is accessible tothe line switch G. This drawing shows also the second selector E(denoted by the dotted rectangle bearing that reference character)accessible to the first selector E.

Figure 2 shows the connector H which is accessible to the selector E,Fig. 1. The connector H has access to a number of lines, of which theparty line on which the substations A A inclusive, are located is one.drawing shows also the common interrupter I and the associated ringinginterrupter relays. Since the system disclosed is a terminal per stationparty line system, the intermediate distributing frame I. D. F. isprovided in ad dition to the main distributing frame M. D. F. Referringnow particularly to Fig. 2, the invention will be described generallywith reference thereto. The line of substation A terminates as usual atthe line side of the main distributing frame M. D. F., and is connectedby the two-wire jumper 168 to the protector side of the M. D. F. Theprotector side of the M. D. F. is connected by switchboard cables to theline switch side of the intermediate distributing frame IQD. F. Thethree conductors for the line switch are taken off the line switch sideof the I. D. F., as shown. Since the line of substation A is a partyline, the associated contacts on the line switch side of the I. D. F.are not jumpered directly to the connector bank side of the I. D. F.,but are connected by means of the jumper 162 to a so-called idler block.one of these being used for each four-party line.

The idler block shown has five sets of terminals. One or" these sets ofterminals is used up by the jumper 162, leaving the other four forjumpers such as 161, between the idler block and the connector bank sideof the The idler block shown, it may be stated, is representative of theothers.

.The contacts of the connector banks are cabled over to the connectorbank side of the I. D. F. and are there connected up in order.

This

Each set of connector bank contacts represents a station which may he astation on an individual line or a station on a party line, dependingupon to where the associated jumper, such as the jumper 161 isconnected.

When a party line station is signalled, it is necessary that thesignalling be done in such a manner that the other stations on the lineare not signalled. In this particular case, the ringers of the stationson a four-party line are connected from either side of the line toground, thus allowing a semi-selection to be made by merely ringing onone side of the line or the other. In order to complete the selection,or, in other words signal the correct subscriber, one ring and tworings, respectively, are assigned to the stations whose ringers areconnected between the same side of the line and ground. This isdesignated in the drawings by the references 2, 2+, etc, the numeralsreferring to the number of bells to which the subscriber is instructedto respond and the minus and plus signs referring to the side of theline to which the ringers are connected.

In order to choose the number of rings and. the side of the line towhich the ringing current is to be appli d when any particular stationis called, a pick-up or ringing relay, such as relay 201 of theconnector H, is provided for each connector. This relay is controlled inaccordance with the cross connection of the bank contacts engaged by theringing current wiper 151 of the connector H, and when energized,connects the common ringing leads 215 and 216 to the called line at thesame time that the ringing current is placed on the proper commonringing lead by one of the ringing interrupter relays 211-2141,inclusive.

The contacts in the bank of wiper 151 of wuich one is provided for eachstation called by way of t is connector H, are cabled to the left-handside of the'l. D. F. along with the line and test contacts as shown.Since there are tour connector bank contacts in each set, the jumpers,such 1-61, are four-conductor jumpers and the fourth conductor of eachconnects with one of the tour pick-up conductors 251254: inclusive,which connected to the idler blocks, as shown. The correct pick-- upconductor is, therefore, connected back to the ringing current terminalof each station, and provides for controlling the ringing relays, suchrelay 201 of the connector H, in such a manner that the common ringingleads 215 and 216 are connected to a called line during the time whenthe desired code is being applied to the iiroper one of theseconductors, the time at which the leads 21.5 and 216 are connected up toa called line depending, in any one case, upon to which of the four setsoi? terminals on the idler block the terminals of the selected stationare connected.

It will be noted that the one ring pick-up conductor 251 is connected.to the bottom terminal of the set 120 on the I. D. F. Thebottomterminals of all such terminal sets are connected to either conductor251 or conductor 253. This bottom terminal and the connection thereto isnot used when the associated line is a party-line, but it is used, as inFig. 1 for substation A, to take care of signalling a subscriber on anindividual line by one ring as is generally done.

The substations, such as A to A inclusive. are of the usual automatictype and have, in addition to the other well-known instrumentalities,calling devices for controlling the automatic switches.

The individual line switches, of which the line switch C is typical, aremechanically of the rotary type of which the wipers have no normalposition and move in a forward dire tion only. The selector andconnector switches such as the selectors E and E and the connector H aremechanically of the wellknown vertical and rotary type of switch and,accordingly, their bank contacts are arranged in horizontal rows orlevels.

The interrupter I may have any desired mechanical construction and, asshown, has an arm or Wiper which is adapted to operate continuously overits field of contacts.

In order to explain the operation of the system, it will be assumed thatthe subscriber at substation A desires to converse with the party linesubscriber at substation A. In order to do this, the subscriber atsubstation A removes his receiver and then dials the directory number ofthe desired subscriber.

l fhen the receiver is removed at substation A, line relay 14 energizesover line conductors 11 and 12. Upon energizing, line relay 14 placesground on private normal conductor 30 at armature 20, thereby making thecalling line busy, and closing a circuit for switching relay 13 andstepping magnet 15 in series. As a further result of the energization ofline relay 14, it connects test wiper 22 to the junction of switchingrelay 13 and stepping magnet 15 at armature 19.

In case the trunk upon which the wipers.

of the line switch are standing is idle, switching relay 13 energizesimmediately. Assuming the trunk to be busy, however, switching relay 13is short-circuited by ground encountered on the busy test contact bytest wiper 22 and does not energize, and the wipers are rotated step bystep by the buzzer-like action of stepping magnet 15, which operatesholding circuit at armature 17, and at armatures 16 and 18 disconnectsline conductors l1 and 12 from the winding of line relay 14 and ground,and extends them by way of wipers 21 and 23, bank contacts 24 and 26,conductors 27 and 29, and armatures 58 and 61 and their resting contactsto the upper and lower windings of line relay 41 of the selector E.

Line relay 41 now energizes over the calling subscribers loop and closesat armature 52 a circuit for release relay 42. Upon energizing,release-relay 42 opens a point in the circuit of release magnet 46 andprepares a circuit for vertical magnet 47 at armature 54, and atarmature 53 places ground on release trunk conductor 28, thereby closingthe usual holding circuit for switching relay 13 of the line switch Cbefore the slow-acting line relay 14 has had time to deenergize.

When the calling subscriber operates his calling device in accordancewith the first digit in the desired number, the circuit of line relay 41is opened a corresponding number of times. Each time line relay 41deenergizes in response to one of the interruptions thereby produced, itcloses a circuit for vertical magnet 47 as follows: from ground by wayof the resting contact of armature 60 and said armature, armature 52 andits resting contact, armature 54 and its working contact, relay 4'3, andvertical magnet 47 to battery. By the operation of vertical magnet 47,the wipers 62-64, inclusive, are raised opposite the desired lever ofbank contacts. Belay 43 is energized in series with vertical magnet 47and, being slow-acting, retains its armature attracted throughout thevertical move ment. As a result of the energization of relay 43, itcloses a circuit at armature 55 for stepping relay 44 by way of 01?normal contacts 51, which close upon the first vertical step, andinterrupter contacts 50. Stepping relay 44, upon energizing, closes alocking circuit for itself at armature 56, and at armature 57 prepares acircuit for rotary magnet 48.

At the end of the vertical movement, slow acting relay 43 deenergizesand completes the circuit of rotary magnet 48 at armature 55. Rotarymagnet 48, upon energizing, advances the wipers 6264, inclusive, intoengagement with the first set of bank contacts in the selected level,and, near the end of its stroke, opens the circuit of stepping relay 44at interrupter contacts 50. Stepping relay 44, upon deenergizing, opensthe circuit of rotary magnet 48 at armature 57 whereupon rotary magnet48 deenergizes also and closes its interrupter contacts 50 again. casethe trunk terminating in the first set of bank contacts is idle,switching relay 45 energizes immediately. Assuming the trunk to be busy,however, switching relay 45 is shortcircuited by the ground potentialencountered by test wiper 63, and stepping relay 44 energizes from thissame ground potential and Inv closes the circuit of rotary magnet 48again, whereupon the switch wipers are rotated inw engagement with thenext set of bank cont acts. This alternate operation of stepping relay44 and rotary magnet 48 continues un- 42; and at armatures 58 and 61disconnects conductors 27 and 29 from the windings of line relay 41, andextends them by way of wipers 62 and 64, bank contacts 65 and 67, andthe associated line conductors to the windings of the line relay of theselector E.

The line and release relays (not shown) of the selector E now energizeand prepares the switch for operation.

When the calling subscriber operates his calling device in accordancewith the second digit in the desired number, the selector E raises itswipers opposite the desired level of bank contacts and then selects anidle trunk. It will be assumed that the trunk selected at this time isthe one extending to the connector H. That being the case, line relay101 of the connector H energizes over the calling line and closes acircuit for release relay 103 at armature 128. Release relay 103, uponenergizing, makes the usual circuit preparations at armatures 130 and131, and at armature 129 places ground on release trunk conductor 75,thereby closing the usual holding circuit for the preceding switches C,E, and E.

When the calling subscriber operates his calling device in accordancewith the third digit in the desired number, a corresponding number ofinterruptions are produced in the circuit of line relay 101. In responseto each of the resulting deenergizations of line relay 101, an impulseof current is sent to vertical magnet 111, the first impulse of currentbeing sent over the following circuit: from ground by way of armature128 and its rest ing contact, armature 131 and its working contact,contact of off normal spring, series relay 104, and vertical magnet 111to battery. By the operation of vertical magnet 111, the switch wipers149l52, inclusive, are raised step by step until they stand opposite thedesired level of bank contacts. Belay 104 is en-- ergized in series withvertical magnet 111 on the first impulse of current and, beingslow-acting, retains its armature attracted throughout the verticalmovement; By attracting its armature 132, relay 104 serves to maintainits own circuit and that of vertical. magnet 111 intact after the offnormal springs have shifted, as they do upon the first vertical step. Atthe end of the vertical movement, relay 104 deenergizes and transfersthe operating circuit from the vertical'to the retary magnet. 7

When the callin subscriber operates his calling device in accordancewith the next and last digit of the desired number, the line relay 101is deenergized a corresponding number of times. Upon each deenergizationof line relay 101, an impulse of current is sent to rotary magnet 112,the first impulse of current being sent over the following circuit: fromground by way of armature 128 and its resting contact, armature 131 andits working contact, normally open contacts controlled by off normalspring 114, armature 132 and its resting contact, resting contact ofarmature 139 and said armature, armature 146 and its resting contact,and rotary magnet 112 to battery. By the operation of rotary magnet 112,the wipers 149- 152, inclusive, are rotated step by step into engagementwith the contacts 153-156, inclusive, of the called line. Relay 108 isenergized in multiple with rotary magnet 112 upon tl e first impulse ofcurrent being delivered to the latter and, being slow-acting, retainsits armature attracted throughout the rotary movement. Upon energizing,relay 108 disconnects test wiper 150 from the upper winding of switchingrelay 109 and connects it to busy relay 105 at armature 141, and atarmature 142 places a shunt around armatures 1.39 of busy relay 107 andits resting contact so as to guard its own circuit and that of rotarymagnet 112 from being opened prematurely by busy relay 107, in case thatrelay energizes during the rotary movement, due to test wiper 150passing over busy test contacts.

Assuming the called line to be busy, busy relay 107 is energized throughtest wiper 150 from ground on contact 154 when the switch wipers stop onthe chosen contacts, and slow acting relay 108, upon deenergizing afterthe last impulse of current is delivered, disconnects itself and rotarymagnet 112 from the operating circuit at armature 142, and at thenormally closed contacts controlled by armature 141 completes a lockingcircuit for busy relay 107, which includes the working contact ofarmature 130 and said armature and armature 138 and its working contact.Since, busy relay 107 is maintained energized, the lead from the busysignalling machine is con nected up to the lower heavy talking conductorat armature 140 and, accordingly, busy tone is sent back to the callingsubscriber to inform him that he cannot obtain the desired connectionfor the time being. Upon hearing this busy tone, the calling subscriberis expected to replace his receiver, whereupon the connection isreleased in a manner similar to that to be described hereinafter.

Assuming now that the called line is idle when called as hereinbeforedescribed, there no ground potential on test contact 154 and busy relay10? is, therefore, not energized when the switch wipers come to restupon the contact associated with the called station. Under theseconditions, slow-acting relay 108, upon deenergizing, completes acircuit for the upper winding of si itching relay 109 in series with thecombined switching and cutoil relay of the called line switch (notshown) The part of this circuit that is shown is as follows: from groundby way of the working contact of armature 130 and said armature,armature 138 and its restingcontact, upper winding of switching relay109,1esting contact of armature 1'41 and said armature, test wiper 150,test contact 154, a conductor of jumper 161, a conductor of jumper 162,and thence by way of the private normal conductor 164 to battery by wayof the cut-off relay of the line switch associated with the called line.The line switch associated with the called l ne as has been explainedhereinbefore, is similar to the line switch C. Accordingly, the cut-offrelay corresponds to cut-off relay 13 of the line switch C and isenergized in series with the associated stepping magnet, similar to thestepping magnet 15 of the line switch C. Due to the usual me chanicalinterlocking device between the armature of the cut-off relay of thecalled line switch and the armature of the associated line relay, thecut-oil relay is energized only half way, and as a result, the wipers ofthe called line switch are not connected up. I

In the connector H, switching relay 109, upon energizing over the abovetraced circuit, closes a locking circuit for itself at armature 145;applies direct ground to test wiper 150 at armature 144; disconnectsrotary magnet 112 and slow-acting relay 108 from the operating circuitat armature 140 connects up the line wipers at armatures 143 and 148;and at armature 147 connects the lower Windin of ringing relay 201 towiper 151 by way or.

arrmiture 136 and its resting contact. When the pick-up conductor 252 isgrounded by the constantly rotating arm of the interrupter 1 coming intoengagement with its contact 218, an energizing circuit is closed forringing relay 201 as follows: from ground by way of the arm ofinterrupter I, piclr-up conductor 252, corresponding conductor of jumper101, bank contact 155, wiper 151, working contact of armature 14'? andsaid armature, resting contact of armature 136 and said armature, andthe lower winding of relay 201 to battery. Relay 201, upon energizing,prepares a locking circuit for its upper winding at armature 232, and atarmatures 203 and 204 shifts the connection of the line Wipers frombattery and ground locally to the two Eventually, the arm of theinterrupter I moves off the pick-up segment 218 and is entirely on theringing segment 219, thereby removing ground from pick-up conductor 252so as to prevent any ringing relays from energizing thereover until thearm of the interrupter I reaches that pick-up position again.

As a further result of the above mentioned energization of relay 213,the common ringing lead-215 is disconnected from battery and isconnected to the right hand winding of the transformer T, which isconnected to battery also, and on which ringing current is superimposedby the generator GEN. through the medium of the left hand winding of thetransformer T. When this occurs,

the ringer at substation A and the other ringer at substation A which isconnected from the top or negative talking conductor to ground, areoperated in the usual manner.

Eventually, the arm of the interrupter I comes into engagement with thelocking segment 220, thereby placing a multipled ground on the lockingconductor 217 so as to maintain the said locking conductor groundedafter the deenergization of relay 213, which occurs subsequently. Afteran interval, the arm of interrupter I passes out of engagement with thesegment 219 and is wholly in engagement with the locking seg- ;ment 220.l Jhen this occurs, relay 213 deenergizes; removes ground from thelockin conductor. 217 at its right hand armature, leaving the saidconductor grounded by Way of the locking segment 220 of the interrupter.I; and at its left hand armature shifts the common ringing conductor215 back to direct battery again, thereby terminating the first ring. 1

vWhen the arm of the interrupter I comes into engagement with ringingsegment 221, Which is multipled with the ringing segment 219 as shown,the circuit of relay 213 is again closed, and the second ringing iseffected upon the ringing lead 215 being shifted to the right handwinding of the transformer T again. The locking conductor 217 ismaintained grounded at the right hand armature of relay 213, While saidrelay 213 is energized.

WVhen the arm of the-interrupter I passes off the segment 221 and comesinto engagement with the dead segment, relay 213 deenergizes andterminates the second ring by disconnecting lead 215 from the right handwinding 01' the ringing current transformer T at its left hand armature.Also, relay 213 disconnects ground from the locking conductor 217 at itsright hand armature, thereby opening the locking circuit of relay 201,whereupon relay 201 deenergizes; opens a still further point in itslocking circuit at armature 232 and at armatures 203 and 204:disconnects the line wipers of the connector from the ringing leads 215and 216, and connects them to battery and ground locally. The deadsegment 222 is placed between the segment 221 and the followingpick-up'segment, to give suliicient time for relay 213 to deenergize andremove the ringing current from the lead 215 before the following pickupconductor 251 is grounded.

The arm of the interrupter I continues to rotate without producing anyparticular re sult so far as the connection in question is concerned,until the pick-up segment 218 as sociated with pick-up conductor 252 isagain grounded. "When this occurs, the above described ringingoperations are repeated.

When the subscriber at substation A responds to the ringing of his bellby removing his receiver, a direct current bridge is closed across theconductors of his line,

whereupon the ring cut-off relay 106 of the connector I-I energizes;extends the line Wipers to the battery feed impedance 102 at its upperand lower 'armatures; and at armature 136 disconnects the lowerwindingof relay'201 from the pick-up wiper 151. The calling and calledsubscribers may now converse with each other in the usual man- -ner.

At the end of the ensuing conversation, the two subscribers replacetheir receivers. The replacing of the receiver at the called substationdoes not produce any particular result, except that battery merely stopsflowing over the called line.

When the receiver is replaced at substation A, the circuit of line relay101 is opened and relay 101 deenergizes. Upon armature 128 beingretracted, the circuit of release relay 103 is opened and a circuit isprepared for release magnet 110. Upon deenergizing in reslow-actingrelease relay 103 removes ground from armature 138 of relay 107 atarmature 130; disconnects ground from release trunk conductor 7 5' atarmature 129, whereupon relays 106 and 109 deenergize; and at armature131 completes a circuit for release magnet 110 by Way of off normalcontacts 113. Upon the energization of release magnet-110, the wipers ofthe connector H are restored to normal position, and the circuit ofrelease magnet 110 is opened at off-normal contacts 113 by the switchshalt when the wipers reach their normal position.

As a result of the ground potentialbeing removed from release trunkconductor 75, switching relay 13 of the line switch G, switching relayof the selector E, and the corresponding relay (not shown) of theselector E decnergize. The deenergization or switching relay 13 of theline switch 0 restores conditions in that switch to normal. lhedeenergization of switching relay of the selector E results in a circuitbeing closed for release magnet l6 at armature and its resting contact.This circuit includes armatures 52 and 5% and their resting contacts andoff-normal contacts Q9. The wipers of the selector E are restored tonormal position in the usual manner upon the energization or" releasemagnet 46, and the circuit of iQlGtLf-ld magnet 4L6 is again opened atoff normal contacts 49 when the switch wipers reach their normalDOSltiOIl. The selector E is restored to normal in a similar manner.

From the foregoing description it is that the subscriber at substation Ais s1 1. also. 1 no subscriber at this substation, however is i structedto respond to the one bell rings only, and the pick-up conductor 251.associated witlr his line so that heis signalled during the ringingperiod which follows immediately after the arm of the interru gter 1 haspassed over the dead contact 229/, at which time-relay 214-is energized.lf'his relay 21 i is energized during the entire perioe, and notdroppedbaclr at the middle of theperiod, as is the relay 213, therebygiving one long ring instead of two short ones.

The'other ringing periods are used tosignal subscribers such thesubscribers at substations A and I3}, whose ringers are connectedbetween the positive side of the line and ground. This is done inexactly the same way as described, except that the ringing cur comesfrom the middle winding of the tra n former T and is projected over thelower or positive line conductor instead of the upper one.

It is evident, then, that a station on a party line can be signalled byeither one or two rings applied to either side of the line and that iicode used or the side to which the ringing current is applied is not atall associated wi h the number of the called station. lit can be seen inconnectionwith l 2, that it the number of. the substation A. is to beassigned to a diiiierent station on account of the sub scriber atsubstation A moving or for some other like reason, the station to whichthat number is assigned can be signalled by either code applied toeither side of the line by merenreneiv 1y placing the jumper 161 on thecorrect set of contacts of the idler block associated with the line inquestion.

Attention is also directed to tne fact that since some of the stationsare signalled by two bells, that is, one ring following imme diatelyafter the preceding ring, it has been found necessary to provide only amomentary pick-up at the beginning of each ringing period, the ringingrelays being held up by a locking conductor which remains groundedLetters Patent will be specifically stated in the appended claims.

What is claimed is:

1. In: a telephone system, a link circuit, line having a plurality ofstations thereon, means for associating said link circuit with saidline, means operating in a'cycle for associ ringing current with saidlinlr circuit, said cycle being divided into as many ringing periodsthere are stations on saidline, each of said periods corresponding toaparticular one of said stations, means for projecting-said ringingcurrent out onsaid line by way oi" said link circuit only during-the rining period corresponding to the desired station, and means for startingsaid projection of ringing current out on said line only at thebeginning of a ringing period.

2. in a party line telephone system, a link circuit, a party line havinga plurality of stations thereon, means for associating said link circuitwith said party line, means continuously operating in successive cyclesfor'associating ringing current with said link circuit, ea h cycle beingdivided into as many ringing periods as there are stations on said line,each of said periods corresponding to a particular one of saidstations,a relay individual-to said link circuit, means for operatingsaid relay only the beginning ofthe ringing period corresponding to thedesired station, ineans 1 for maintaining said relay operated onlyduring said period, and means controlled by said relay tor propectmgsaid ringing current out on said line each time said relay is ope ated.

8. In a selective ringing party line telephone syst-ein, a signallingcircuit, a relav for connecting said circuit to a called party line,

and a ringing machine for periodically alter ing the character oi" saidcircuit to' adapt the same for signalling all the stations on saidlinein turn, said machine also comprising means for energizing said relayonly at the begmnmgof the period when the said circuit is of such acharacter that it will signal the wanted station.

l. in a selectiveringing party line telephone system, a signallingcircuit, a relay for connecting said circuit to a called party line, aringing machine for periodically altering the character or" said circuitto adapt the same for signalling all the stations on said line in turn,said machine also comprising means for energizing said relay only at thebeginning or the period when the said circuit is of such a characterthat it will signal the wanted station, and separate means formaintaining said relay energized during the elapse of said period.

5. In a telephone system, a party line, a connector switch, means foroperating said switch to connect with said line, two common signallingconductors, one for each side of said line, means for applyingsignalling current alternately to said conductors, a signal connected toone side of said line, and means for connecting said common conductorsto said line only during the time that ringing current applied to thatcommon conductor corresponding to the side 01 the line to which saidsignal is connected.

6. In a telephone system, a party line, a station on said line, aconnector switch, means for operating said switch to connect with saidline, two common signalling conductors, one for each side of said line,means for applying signalling cu rent to said conductor alternately, asignal at said station connected to one side of said line, means forconnecting said common conductors to said line only during the time thatringing current is applied to the common signalling conductorcorrespending to the side of the line to which said 1 signal isconnected, and means operative responsive to the subscriber at saidstation answering said signal for rendering said last connecting meansineffective.

7. In a selective ringing party line telephone system, means forextending a connection to a called party line, a plurality ofringcontrol conductors one of which is select ed when the connection isestablished, each control conductor corresponding to a different stationon said line, two common signalling conductors, means for applying coderinging current to each signaling conductor alternately, and meanscontrolled over the selected control. conductor for connecting saidcommon signalling conductors to the called line only when theproper codeof ringing current is applied to the proper signalling conduct-or tosignal the desired station on said line.

8. In a selective ringing party line tele phone system, meansforextending a connection to a called parry line, a plurality of ringingcontrol conductors one of which is selected when the connection isestablished, each control conductor corresponding to a difierent stationon said line, two common signalling conductors, means for applying coderinging current to each signalling conductor alternately, a relay forconnecting said signalling conductors to the called line, means forenergizing said relay only at the beginning of the application of theproper code of ringing current to the proper signalling conductor tosignal the desired station on said line, and means for maintaining saidrelay energized during the application of said code to said signallingconductor.

9. In a telephone system, a connector, a called party line, a pluralityof branches of said line accessible from the connector, code signallingmechanism for applying signalling current to the called line in apredetermined series of alternate live and dead periods, automaticallyapplied means for causing the signalling current to beapplied to thecalled line only at the starting of the first live period of the nextseries responsive to the operation of the connector in effectingconnective relation with the called line regardless of the time saidoperation occurs, and automatically applied means for causing a specificsaid code series of signalling current to be applied to the called linein corre- 5 spondence with the branch of the called line the connectoris operated into connective relation with so that a different codeseries of signalling current will be applied to the called linedepending upon what branch of the called line is connected with.

'10. In a telephone system, a connector, a called party line, aplurality of branches of said line accessible from the connector, codesignalling mechanism for applying signalling current to the called linein a predetermined series of non-uniform alternate live and deadperiods, automatically applied means for causing the signalling currentto be applied. to the called line only at the starting of the first liveperiod of the next series responsive to the operation of the connectorin effecting connective relation with the called line regardless of thetime said operation occurs, and automatically applied means for causinga specific said code series of signalling current to be applied to thecalled line in correspondence with the branch of the called line theconnector is operated into connective relation with so that a differentcode series of signalling current will be applied to the called linedepending upon what branch of the called line is connected with.

11. In a telephone system, a connector, a called party line, a pluralityof branches of said line accessible from the connector, code signallingmechanism for applying signalling current of any one of a plurality ofdifferently effective characters to the called line in a predeterminedseries of alternate live and dead periods, automatically applied meansfor causing the signalling current to be applied to the called line onlyat the starting of the first live period of the next series responsiveto the operation of the connector in effecting connective relation withthe called lineregardless of the time said operation occurs, andautomatically applied means for causing a. specific said code series ofspecific said character of current to be applied to the called line in.correspondence with the branch of the called line the connector isoperated into connective relation with sothat a different code series ofsignalling current of a specific said character will be applied to thecalled line depending upon which branch of the called line is connectedwith.

12. In an automatic telephone system, a connector, a plurality of linesaccessible from the connector, a source of signalling current. abusy-test terminal for each line, a terminal specific to each line forcontrolling the application of said source of signalling current to itscompanion line in a specific manner, a wiper of the connectorcooperative with the respective said specific terminals when a ran- 1dom said line companion thereto is connected to by the connector, relaymechanism opera tive to prepare a signalling current path to theconnected line, and means controlled over said specific terminal of theconnected line 1 to operate the relay mechanism.

13. In an automatic telephone system, a connector, a plurality of linesaccessible from the connector, a source of signalling current havingintermittent live periods and a ter- .minal therefor specific to eachsaid line for controlling the application of said source of signallingcurrent to its companion line in a specific manner, a wiper of theconnector cooperative With the respective said terminals when a randomsaid line companion thereto is connected to by the connector, relaymeclianism operative to prepare a signal circuit path to the connectedline, and means controlled over the said specific terminal of theconnected line to operate the relay mechanism only at a predetern'iinedtime with correspondence to the requirement ofsaid specific manner.

In witness whereof, I hereunto subscribe my name this 26th day ofJanuary, A. D. 1926.

RODNEY G. RICHARDSON.

In witness whereof, I hereunto subscribe my name this 26th day ofJanuary, A. D. 1926.

JOHN l. BELLAMY.

